Content display devices such as smartphones, netbooks, gaming devices, PDAs, desktop computers, televisions, and laptop computers are now ubiquitous. And these devices now very commonly include hardware that provides network connectivity to web servers and software (e.g., web browsers) that provide an interface for users to request and view content from these web servers.
When a web page is being loaded by a web browser, due to the potentially long time it takes to obtain and process all the data from the Internet, the browser often displays an incomplete version of the page with content that is already loaded and processed while the rest of the page is being loaded. By displaying an incomplete version, the user can start reading part of the page instead of seeing a blank screen. Users have become accustomed to being able to view at least some content on a page as quickly as possible, and therefore, current web browsers and content display devices together often utilize a significant amount of processing power to display that content. Very often, these incomplete versions of the web page are displayed for only a short period of time. Yet they are still computationally expensive (and use a lot of power) to render.
The rendering process includes 1) determining the layout of the page by parsing style sheets (e.g., CSS); 2) converting the laid out HTML elements into graphics elements; 3) rasterizing graphics elements into bitmaps using a graphics library; and 4) compositing the bitmaps onto the screen. These steps are done for each incomplete version of the page during a page load, as well as for the final completely loaded version of the page. This involves significant processing and increased power usage in comparison to rendering just one version of the webpage.